Novel oncologic drugs: what they do and how they affect images.

Targeted therapies are designed to interfere with specific aberrant biologic pathways involved in tumor development. The main classes of novel oncologic drugs include antiangiogenic drugs, antivascular agents, drugs interfering with EGFR-HER2 or KIT receptors, inhibitors of the PI3K/Akt/mTOR pathway, and hormonal therapies. Cancer cells usurp normal signal transduction pathways used by growth factors to stimulate proliferation and sustain viability. The interaction of growth factors with their receptors activates different intracellular pathways affecting key tumor biologic processes such as neoangiogenesis, tumor metabolism, and tumor proliferation. The response of tumors to anticancer therapy can be evaluated with anatomic response assessment, qualitative response assessment, and response assessment with functional and molecular imaging. Angiogenesis can be measured by means of perfusion imaging with computed tomography and magnetic resonance (MR) imaging. Diffusion-weighted MR imaging allows imaging evaluation of tumor cellularity. The main imaging techniques for studying tumor metabolism in vivo are positron emission tomography and MR spectroscopy. Familiarity with imaging findings secondary to tumor response to targeted therapies may help the radiologist better assist the clinician in accurate evaluation of tumor response to these anticancer treatments. Functional and molecular imaging techniques may provide valuable data and augment conventional assessment of tumor response to targeted therapies. Supplemental material available at http://radiographics.rsna.org/lookup/suppl/doi:10.1148/rg.317115108/-/DC1.

The role of functional imaging in colorectal cancer.

OBJECTIVE: This article reviews the current and future contributions of functional imaging techniques to improve diagnosis, prognosis, and treatment of colorectal cancer. In addition, evolving roles and challenges for their implementation will be covered. CONCLUSION: Functional imaging now has a growing role in colorectal cancer. Recent developments in imaging technologies and validation of these newer imaging techniques may lead to significant improvements in the management of patients with colorectal cancer.

Imaging arteriovenous fistulas.

OBJECTIVE: Arteriovenous fistulas (AVFs) are abnormal communications with shunting of blood from an artery to a vein. AVFs mainly involve the peripheral vascular system but can affect virtually any organ or system in the body. They may be congenital, created surgically for hemodialysis, or caused by pathologic processes. This review describes the diverse origins of AVFs and illustrates the spectrum of imaging findings at radiography, ultrasound, CT, MRI, and digital angiography for AVFs in different locations: the CNS, thorax, abdomen, musculoskeletal system, and peripheral vascular system. We also discuss syndromes associated with AVFs and describe recent interventional techniques for treating AVFs. CONCLUSION: Familiarity with the spectrum of imaging findings in AVFs is essential for the accurate interpretation of images and facilitates diagnosis and therapeutic management. Radiologists can play a critical role in the diagnosis and treatment of AVFs. Digital angiography is helpful in elaborating a vascular map for endovascular treatment.